Devices coupled to a power outlet or directly wired into a power grid can vary their consumption over time. When powered off, the consumption can be small or zero depending on the device. When powered on and operating properly, the power consumption can vary according to use and other factors (heat, age, etc.). When operating defectively, power consumption can be large, unpredictable and potentially dangerous. Each device typically operates in a vacuum, that is as a standalone unit that is neither monitored nor controlled remotely.